Multiunit electron tube



y 29, 947 w. w. @m H AL 2,424,684

MULTIUNIT ELECTRON TUBE Filed April 27, 1946 s Sheet s-Shee1i l INVENTORS William W. E/fe/ ack A. M Cu/loa 1'1 ATTORNEY July 29, 1947. w E|TE| ET AL 2,424,684

MULTIUNIT ELECTRON TUBE Filed April 27, 1946 s Sheets-Sheet 2 11v TORS Will/am W- E/' v ina -k AME Cul/ou ATTORNEY y 1947- w. w. EITEL ET AL 2 uuurwm'r summon TUBE Filed April 21, 1946 v 5 Sheets-Sheet s IN VEN TORS William W. E/fe/ Jack 14. M9 Cal/(ugh ATTORNE. Y

July 29, 1947. i 'w, w, Err L r AL 2,424,684

MULTIUNIT'ELEGTRON TUBE Filed April 27, 1946 5 Sheets-Sheet 4 INVENTORS William w. Ei'f'e/ -dack' AME Cul/ uy/r ATTORNEY July 29, 1947- w. w. EITEL ET AL 2,424,684

MULTIUNIT ELECTRON TUBE I Filed April 27, 1946 5 Sheets-Sheet 5 IN VEN TORS Hi! I iam W. Ei-I'eI BY Jack A. ME CgZ/Ogg/I ATTORNEY Patented July 29, 1947 UNITED STATES PATENT OFFICE lough, Millbrae, Calif.,

assigncrs to Eitel- McCullough, Inc., SanBruno, Calif., a corporation of California Application April 27, 1946, Serial No. 665,366

11 Claims.

Our invention relates to electron tubes of the power or transmitting tube type, and more particularly to improvements in multi-unit tubes of the character disclosed in our copending application, Serial No. 645,441, filed Feb. 4, 1946.

The trend in electron tube design is toward tubes capable of operation at the higher frequencies. It is not difiicult to achieve the desired electrical properties for good operation. at high frequencies with tubes of small physical size because small tubes have certain inherent advantages from the standpoint of tube structure and geometry, such as maintaining closer electrode spacings and lower inductance leads. The disadvantage of small structures for power tube uses is the limitation on power output due to lack of heat dissipation from the electrodes, particularly from the anode. In other words, large physical size is incompatible with electrical properties required for higher frequency operation, and this would appear to put a ceiling on power output for high frequency tubes.

The broad object of our invention is to provide a tube capable of large power output without sacrifice of those electrical properties required for high frequency operation.

Another important object is to provide a tube structure which simplifies the manufacture of power tubes, and which enables a variety of tubes of different power ratings to be built, all from basic tube units made alike.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure I is an elevational view of an air cooled tube embodying the improvements of our invention incorporating a plurality of tetrode units; and

Figures 2 and 3 are top and bottom views, respectively, of the same.

Figure 4 i a vertical sectional View of the tube. 4

Figure 5 is a view similar to Figure 4 showing a modified construction showing a water cooled tube incorporating a plurality of triode units.

In terms of broad inclusion, our electron tube comprises a plurality of tube units, preferably arranged in a circle. Each unit preferably comprises an envelope having a portion forming an anode, and a cooler structure is provided, preferably common to the anodes of the units.

The cooler may have fins for air cooling, or may be of jacket construction for water cooling. Terminals are provided for the electrodes of the tube units, and these terminals are preferably common to electrodes of the several units. A metallic member extending transversely of the tube units serves as a support for the units and also as a grid terminal. In our preferred construction, embodylng tetrode units, this transverse member also functions as a shield between input and output elements.

In greater detail, Figures 1 to 4 show an air cooled tube embodying tetrode units 2. We show eight units arranged in a circle about a vertical axis, but it is understood that a greater or less number of units may be employed in the tube. The tetrode units each comprise an anode 3, cathode 4, control grid 6 and screen grid 1. Tube units 2 are each complete tube units, independently constructed and evacuated.

Anodes 3 are of the external anode type adapted. for cooling by forced air or the like, and are connected to a cooler structure 8 which is preferably common to the anodes of the several units. This cooler structure is of annular shape to accommodate the circular arrangement of the tube units and also functions as a support for tying the units together.

Anodes 3 are preferably formed as portions of the envelopes of the tube units. The anodes illustrated comprise a tubular body of metal, such as copper, carrying an exhaust tubulation 9 at the top and a sealing flange l i adjacent the bottom. Metallic tubulation 9 is pinched off at tip [2 after evacuation of the envelope. Flange H is sealed to a cylindrically-shaped envelope section l3 of vitreous material such as glass.

While we show tube units embodying substantially full external anodes, it is understood that the anodes may be the internal-external type wherein the outwardly projecting portion of the anode functions largely as a, heat conducting member. In any event the outwardly projecting portions of the anodes are connected to the cooler structure 8, the extent to which the anodes extend into the envelope being immaterial from the standpoint of our invention.

The internal electrodes 4, 6 and l of each unit are preferably supported from the lower portion of the envelope. As illustrated, a Vitreous disk l6 sealed to a metallic ring ll provides a closure for the lower endof the envelope, ring ll being sealed to envelope section I3 so that this ring forms part of the envelope wall. Screen grid I which extends into anode 3 is supported by a metallic bracket l8 secured to ring I! so that this ring functions as a lead-in conductor for the screen grid. Grid support l8 extends transversely of the envelope and also functions as a shield between the anode 3 and the lower portions of the envelope.

Control grid 6 which extends into the screen grid is supported on a, lead-in conductor or rod 2| arranged below shield l8 and sealed to disk I 6. It will be observed that screen grid 1 and its associated shield It provides internal 'electrostatic shielding structure interposed between the input and output electrodes. In the tube illustrated, when operated in the usual manner as a grounded cathode amplifier, the control grid 6 is the input electrode and the anode .3 is the output electrode. The cathode illustrated is a, double spiral filament secured to lead-gin conductors 22 sealed to disk l6. While we show a filamentary type of .cathode, it is understood that an indirectly heated typemaybe employed.

.Cooler structures, which is adapted for cooling ,by forced air, comprises a ring-shaped core .23 of metal, such .as copper, having recesses 24 for receiving anodes .3 of the units. The anodes are secured to .core .23 by a fusible bonding material 26 of cadmium solder ,or the like. Radially extending fins .2] are provided on core .23 to further .enhance removal .of heat from the anodes, these fins being preferably arranged on both the inner and outer surfaces of the cooler core. For convenience in manufacture we preferably form the line by corrugating a continuous strip .of .metal and placing it between the core and ,a retaining sleeve 28. .An annular 'cap 2.9 covering the upper ends of the anodes completes the cooler structure.

In operation .of our tube .an air stream is :directed axially of the tube, which .air divides and passes through the center of the tube as well as along the outside, thus fiowing .past .both sets of fins .27. The air flow may be directed either upwardly For downwardly. In .either case .the central column of air functions .to .cool the porticns .of the tube envelopes which lie inside the circle. The arrows in Figure .4 show the flow .of a downwardly directed stream.

The lower portions of the tube units are tied together .by a circular support member .3l .extending transversely of the .main .axis. This member is preferably of metal and, in .the tube .beingdescribed, also functions .as a screen .grid terminal .and an electrostatic shield externally of the units. Asbest-shown in Figure 4, member SJ is disk-shaped, preferably somewhat dished, and has .a series .of apertures :for receiving the lower ends of the envelopes of the tube units. Resilient fingers 32 bordering the apertures releasably engage the envelopes so that the tube units may be plugged into the support member .31. These fingers make contact with rings :l'! of the envelopes so that member 3i forms acornmon terminal .for the screen grids .of the several A central opening in member 3!, covered by a metallic screen 33, permits downward -fiow of air, and a conical flange 34 bordering the opening serves to direct some .of the air outwardly past theenvelopes of the tube units.

It will be observed that member 3! forms a continuation of internal shields It so that shielding means is provided internally and externally of the tube units to electrostatically shield the input circuit elements from the output circuit elements. In our tube the screen grids 1, internal shields l8 and external shield 3| all comprise part of the shielding means; it being noted that anodes 3 lie above the shielding means, and that the control grids S and the conductors therefore lie below the shielding means.

'I-erminal v3,6, which is common to the control grids of the several units, is supported below member 3| by insulating spacers 35. This control grid terminal is centrally located and is preferably of metallic tubing having a flange 3! to which flexible conductors 38 from the control .grid leads 2'! are connected.

A pair of cathode terminal rings 39 are supported below member 34 by insulating spacers M. These metallic rings are concentric with the ,main axis of the tube and are disposed about the control grid terminal 36. The filamentary cathodes are connected in parallel to rings 39 by flexible conductors 42. Filament heating cur- ,rent is supplied through suitable conductors 43 connected to rings 39.

While we have first described.atubeembodying tetrode units, it is understood that these units may be of other tube types, such as diodes or triodes. Likewise, a cooling medium other than air may be employed. Figure 5 shows a water cooled tube embodying triode units. In this case, the control grid 46 is mounted similar to the screen grid-in the .tube unit first described. Member .31 therefore functions as the terminal for the control grids.

The cooler of the tube structure in Figure 5 comprises a hollow annular jacket 47 having recesses for receiving the anodes. A cooling fluid, such as water, circulates around the circular cooler from an inlet 418.150 an .outlet 63.

While we haveshown .acooler structure which is in the form of a continuous ringcommon to the several .units, it is understood that the cooler may .be of.sectionalconstruction so that each unit carries a separate section of the coolerstructure. In the latter casethe member 3.! serves to physically tie ,the units together in the tube. The common cooler structure has the advantage of providing additional means for tying the units together, while the sectional cooler structure is easier to assemble.

We .claim:

11,. A multi-unit electron tube comprising a plurality of tube units rigidly connected together as asingle structural body, each unit having an individual envelope with an output-electrode-and an input electrode, conducting means afiording a direct electrical connection between the col-r sponding electrodes of the several tube units, and shielding means internally and externally of said units and interposed between the input and output electrodes and the respective conducting means therefor.

2. ,Amulti-unit electron tube comprising a plurality of tube units .disposed with their axes parallel .to a common central axis and rigidly connected together as a single structural body, each unit having an individual envelope with an input electrode and an outputelectrode, shielding means extending transversely of said axis, and commonconductor .means fortheinput electrodes separated from the output electrodes by said shielding means.

-3. A multi-unit electron tube-comprising a pluralityof tube units disposed with their axes parallel to a common central axis and rigidly connected together as a single structural body, each unit .having an individual envelope with an input electrode and an output electrode, shielding means extending transversely of said aids internally and externally of said units and interposed between the input and output electrodes, and common conductor means for the input electrodes separated from the output electrodes by said shielding means.

4. A multi-unit electron tube comprising a plurality of tetrode units rigidly connected together as a single structural body, each unit having an individual envelope with an anode and screen grid and control grid, and common shielding means for said units, said shielding means being electrically connected to the screen grids, extend ing outwardly therefrom, and externally of said units.

5. A multi-unit electron tube comprising a plurality of tetrode units rigidly connected to gether as a single structural body, each unit having an individual envelope with an anode and screen grid and control grid, and common shielding means for said units, said shielding means being electrically connected to the screen grids, extending outwardly therefrom, and externally of said units, and common conductor means for the control grids separated from the anodes by said shielding means.

6. A multi-unit electron tube comprising a plurality of tube units disposed with their axes parallel to a common central axis and rigidly connected together as a single structural body, each unit comprising an individual envelope having an upper portion forming an anode, a cooler structure carried by the anodes of said units, a control grid in each envelope, shielding means extending transversely of said axis below the cooler structure, and common conductor means for the control grids below said shielding means.

7. A multi-unit electron tube comprising a plurality of tube units rigidly connected together as a single structural body, each unit comprising an individual envelope, a grid in the envelope of said unit, a shield in each envelope connected with the grid, and a common shield externally of the envelopes registering with the internal shields.

8. A multi-unit electron tube comprising a plurality of tetrode units rigidly connected together as a single structural body, each unit comprising an individual envelope carrying an anode, a screen grid and control grid in each envelope, a shield in each envelope connected with the screen grid, a common shield externally of the envelopes registering with the internal shields, and common conductor means for the control grids separated from the anodes by said shields.

9. A multi-unit electron tube comprising a plurality of tube units disposed with their axes parallel to a common central axis and rigidly connected together as a single structural body, each unit comprising an individual envelope hav ing a portion forming an external anode and another portion forming a grid connector ring, a cooler structure carried by the anodes, a grid in each envelope connected to said ring, a cathode in each envelope, a metallic member extending transversely of said axis below the cooler structure and connected to said rings of the envelopes, and conductors for the cathodes below said member.

10. A multi-unit electron tube comprising a plurality of tube units disposed with their axes parallel to a common central axis and rigidly connected together as a single structural body, each unit comprising an individual envelope having a portion forming an external anode and another portion forming a grid connector ring, a

circular cooler structure carried by the anodes, a grid in each envelope connected to said ring, a cathode in each envelope, a circular metallic member extending transversely of said axis below the cooler structure and connected to said rings of the envelopes, and a pair of ring-shaped conductors for the cathodes below said member.

11. A multi-unit electron tube comprising a plurality of tube units disposed with their axes parallel to a common central axis and rigidly connected together as a single structural body, each unit comprising an individual envelope having a portion forming an external anode and another portion forming a screen grid connector ring, a cooler structure carried by the anodes, a screen grid in each envelope connected to said ring, a control grid in each envelope, a metallic member extending transversely of said axis below the cooler structure and connected to said rings of the envelopes, and a common conductor for the control grids below said member.

WILLIAM W. EITEL. JACK A. MCCULLOUGH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,066,674 Dunmore et a1 Jan. 5, 1937 2,105,506 Ronci Jan. 18, 1938 1,437,498 De Forest Dec. 5, 1922 2,408,927 Gurewitsch Oct. 8, 1946 

